Organismal Biology Lecture 1 PDF

Biology 170: Organismal Biology Lecture 1: Introduction  What is life? Living thing Not a living thing Meeko Roomba  What are some key characteristics that make something a living thing? Why do we consider Meeko a livin...

Biology 170: Organismal Biology Lecture 1: Introduction  What is life? Living thing Not a living thing Meeko Roomba  What are some key characteristics that make something a living thing? Why do we consider Meeko a living thing, but not the Roomba?  What is life? Textbook: “…life defies a simple, one- sentence definition” Properties and processes we associate with life:  What is life? Meeko Roomba Structural organization Response to environment Energy processing Regulation (homeostasis) Growth and development Reproduction Evolutionary adaptation  Traits Shared by Living Organisms Consist of one or more cells – Cells can be prokaryotic or eukaryotic – Organisms can be unicellular or multicellular Unicellular Multicellular  Traits Shared by Living Organisms Consist of one or more cells Multicellular – Organisms are built Organism hierarchically from cells Organs Unicellular Tissues Cell (= organism) Cells Molecules Molecules Atoms Atoms  Hierarchical organization of biological systems  Traits Shared by Living Organisms Consist of one or more cells – Organization creates complexity – Emergent properties at each level  Traits Shared by Living Organisms Respond to their environment – Stimulus and response – Physiological change in organism  Traits Shared by Living Organisms Capture energy from the environment and use it to do biological work  Traits Shared by Living Organisms Maintain constant internal conditions (homeostasis) – Requires energy  How does your body achieve homeostasis?  Traits Shared by Living Organisms Contain genetic information used to develop and reproduce themselves – DNA – RNA – Amino acids – Proteins – Proteins make things happen  Traits Shared by Living Organisms Contain genetic information used to develop and reproduce themselves Protein Trait  Traits Shared by Living Organisms Contain genetic information used to develop and reproduce themselves  Traits Shared by Living Organisms Contain genetic information used to develop and reproduce themselves – DNA is replicated and passed on during cell division Is this process perfect? – All cells are made from the division of previous cells  Traits Shared by Living Organisms Capacity for evolution – Change in genetic makeup of a population over time – Adaptation – change that increases chances of survival or reproduction  Evolution and Life Unity of life: All living things are descended from a common ancestor Diversity of life: Differences among living organisms result from evolutionary changes over time  Scientific Method How do we know anything about the world around us? 1. Observations with our senses 2. Our interpretation of these observations Understanding of our observations comes from one or more “ways of knowing”: – Belief (e.g., religion) – Logic (e.g., philosophy) – Science  Scientific Method Science – a way of understanding the natural world based on the accumulation of observable, testable, and repeatable evidence  Scientific Method 1. Observation – Using senses or instruments to take measurements (data) – Qualitative – descriptive – Quantitative – numerical  Scientific Method 1. Observation – Amphibian populations are declining in size. Houlahan et al. 2000  Scientific Method 2. Question – Why are amphibian populations in decline?  Scientific Method 3. Hypothesis – A possible answer to your question – H1: Exposure to agricultural chemicals (e.g., atrazine) causes reproductive abnormalities in amphibians. – Must be testable and falsifiable  Scientific Method 4. Predictions – The results you expect to observe – P1: If H1 is true, then frog tadpoles exposed to atrazine should develop reproductive abnormalities.  Scientific Method 5. Experiment – Collect evidence to test predictions – Controlled experiments or observational tests – Must be reproducible  Scientific Method 5. Experiment – Independent variable – Dependent variable – Controls remove other variables and provide a comparison 0 ppb 0.1 ppb 25 ppb  What would you control?  Which treatment is a control?  Scientific Method 6. Analyze data 7. Make conclusions DV IV  What do the data indicate?  Scientific Method Results either reject or support our hypothesis We never “prove” a hypothesis, because future research could contradict our evidence  Scientific Method Science is: – Iterative – Self-correcting – Consensus-based  Scientific Method Some relevant definitions: – Fact – an objective, verifiable observation (a piece of data) – Hypothesis – a tentative explanation for a pattern of observations – Theory – a general explanation that has been tested many, many times without being rejected; a hypothesis that is extremely likely to be correct (based on repeated testing)  Practice Work in groups of ~4 Everyone come up with a simple hypothesis Choose 1 hypothesis for your group Design an experiment to test this hypothesis – What are your independent and dependent variables? – What data will you collect? – Do you have a control group? What else will you control?  Study Questions How might you define "life"? What are some key similarities among all living organisms? Why do all living organisms share those key similarities? Explain the hierarchy of biological organization. What are emergent properties? Give an example. How does DNA determine an organism’s characteristics? How does science differ from other ways of knowing (e.g., religion)? What are the typical steps in carrying out the "scientific method"? What are the requirements of a valid hypothesis? What are the requirements of a good experiment? What are independent and dependent variables? When testing predictions of a hypothesis, why are controls helpful? Compare and contrast hypotheses and theories.